In the installation of conventional wall to wall carpeting, it is the usual practice to anchor tackless carpet strips about the periphery of the room and then to affix the carpet in place over the floor by anchoring the peripheral edges of the carpet to the tackless strips. In order to produce a satisfactory installation of the carpet without ripples, creases, looseness or other defects in installation, it is the usual practice to employ suitable tools to stretch the carpet sufficiently prior to permanently engaging the peripheral edges of the carpet to the tackless strips.
The tools conventionally employed for carpet stretching purposes are manually operated and generally comprise three distinct types of tools, namely, a knee kicker, a pole stretcher type or an anchor blade type of device.
The knee kicker is a relatively small tool which comprises generally a carpet gripper head and a padded body suitable for receiving impacts from the knee of the installer to push the carpet gripper head forwardly to thereby stretch the carpet. Such devices are relatively easy to operate by a single workman, but are limited in operation and in function by their inability to develop suitable power to stretch the carpet, especially where large rooms are involved.
The pole stretcher type of installation tool comprises a carpet gripper head and an elongated pole which extends from one sidewall of the room to enable the tool to push against the sidewall as the carpet is stretched toward the opposite sidewall. Usually a manual handle functions a lever mechanism to push the carpet gripper head towards the tackless strip for carpet stretching purposes. This tool also required considerable strength and the use of both hands of the operator. Further, regulation of the length of stretch is fixed by the design of the lever mechanism and this cannot be adjusted by the operator.
The anchor blade type of installation tool comprises essentially a carpet gripper head and an anchor blade for positioning behind the tackless strip. Usually an elongated operating handle is employed to function through a leverage principle to pull the carpet gripper head toward the anchoring blade to thereby stretch the carpet in the path of travel. Such devices develop sufficient power to adequately pull and stretch the carpet but require considerable strength and the use of both hands of the operator.
As described by Muller et al. in U.S. Pat. No. 5,145,225, carpet manufacturers recommend that jute-backed tufted carpets be stretched “drum-tight”. The amount of stretch needed for a polypropylene backed carpet is usually calculated as one and a half percent of the carpet length and width. The amount of stretching required is further complicated for jute-backed carpeting of lengths longer than 7 meters because the carpet tends to drag against the underlay and make the stretch “feel” tighter than it really is. In addition the amount of stretch required for a particular type of carpet varies between carpets produced by different manufacturers.
As a consequence a carpet installer is usually a highly experienced well practiced individual who is capable of making a qualitative judgement whether or not he has stretched a carpet properly. If the judgement is incorrect the carpet usually requires restretching. If the carpet is overstretched and begins to contract after settling the carpet in question might have to be replaced at the expense of the carpet installer.
Inclusive of the teaching of Muller et al. it is also known in the prior art to use hydraulic, electric and pneumatically actuated carpet stretchers. For example, applicant is aware of U.S. Pat. No. 4,042,211 which issued Aug. 16, 1977 to Hammond et al. for a Portable Device for Stretching and Installing Carpet. The Hammond device is taught to include a cylinder carried by a handle, the handle member having a spring biased piston, a piston rod connected to the piston extending through one end of the cylinder and having a leg member depending from the piston rod for engaging the carpet to be installed. A support member is disclosed which depends from one end of the handle member for mounting behind a floor mounted wood strip to which the carpet is to be attached. The piston is moved so as to stretch the carpet engaged by the leg member toward the support member so that the carpet may be attached to the floor mounted wood strip.
U.S. Pat. No. 4,084,787 issued Apr. 18, 1978 to Kowalczyk for a Carpet Installation Tool which includes a portable body having an anchoring blade to engage behind a tackless carpet strip, the body having a carpet gripper head including pins for engaging the carpet and stretching the carpet upon a motor moving the carpet gripper ahead relative to the anchoring blade so as to stretch the carpet engaged by the pins.
As noted above, U.S. Pat. No. 5,145,225 issued Sep. 8, 1992 to Muller et al. for a Carpet Stretcher. The carpet stretcher of Muller includes a retractable carpet engaging head which is pneumatically driven by a cylinder. The cylinder is mounted to a frame. The frame supports a face plate extension adapted for location behind a tackless strip so that the carpet stretcher may stretch carpet towards an adjacent wall to engage a carpet edge with the tackless strip.
U.S. Pat. No. 6,371,446 issued Apr. 16, 2002 to Gauthier et al. for a Hand-Held Pneumatic Carpet Stretcher. The carpet stretcher of Gauthier et al. is powered by compressed air and includes a gripper plate which holds a front end of the carpet stretcher stationary behind a carpet tack strip, and teeth which pull the carpet towards the tack strip when pistons are pneumatically retracted.